Undernutrition and infectious diseases are tightly linked in a self-reinforcing cycle. Childhood episodes of diarrhea, pneumonia and measles are exacerbated by undernutrition, which significantly contributes to the death toll from these infections. In this feature, the VoICE team explains the cycle of malnutrition and infectious disease, and brings you evidence of the ways in which vaccines interrupt this cycle and help to protect the overall health, growth and physical development of vulnerable children.